Golgi-resident small GTPase Rab33B interacts with Atg16L and modulates autophagosome formation.

Macroautophagy is a mechanism of degradation of cytoplasmic components in all eukaryotic cells. In macroautophagy, cytoplasmic components are wrapped by double-membrane structures called autophagosomes, whose formation involves unique membrane dynamics, i.e., de novo formation of a double-membrane sac called the isolation membrane and its elongation. However, the precise regulatory mechanism ...
of isolation membrane formation and elongation remains unknown. In this study, we showed that Golgi-resident small GTPase Rab33B (and Rab33A) specifically interacts with Atg16L, an essential factor in isolation membrane formation, in a guanosine triphosphate-dependent manner. Expression of a GTPase-deficient mutant Rab33B (Rab33B-Q92L) induced the lipidation of LC3, which is an essential process in autophagosome formation, even under nutrient-rich conditions, and attenuated macroautophagy, as judged by the degradation of p62/sequestosome 1. In addition, overexpression of the Rab33B binding domain of Atg16L suppressed autophagosome formation. Our findings suggest that Rab33 modulates autophagosome formation through interaction with Atg16L.
Mesh Terms:
Animals, Autophagy, COS Cells, Carrier Proteins, Cell Membrane, Cercopithecus aethiops, GTP Phosphohydrolases, Gene Expression Regulation, Enzymologic, Golgi Apparatus, HeLa Cells, Humans, Mice, NIH 3T3 Cells, Phagosomes, rab GTP-Binding Proteins
Mol. Biol. Cell
Date: Jul. 01, 2008
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